I got a few Mitsumi M28N-1 motors with built in encoders cheap off of ebay.
They seem to work ok, but unfortunately did not come with any pinout. It looks like the pins are layed out this way:
Mitusmi M28N-1 Pinout:
Blue (1): Motor A
Green (2): Motor B
Yellow (3): Encoder Voltage, 1.1 – 1.2V
Black (4): Encoder Ground
Red (5): Encoder Signal
I hooked up a resistor (~500 Ohms, selected at random) between the signal line and sensor ground.
The encoder power line seems to work if provided 10mA – 20mA, and quickly shorts and goes non conductive after that, so it looks like it is a LED with forward voltage around 1.2V. The signal line will be a square wave with frequency proportional to the spin rate, and magnitude a bit less than 400mV (probably will be a bit more or less depending on resistor value), testing with the datasheets rpm vs voltage chart shows the motor is fairly close to what is spec’d (will have table later)
In order for this to work as an interrupt input on my AVRs i will probably need to amplify and filter the signal a little bit, with a common emitter amplifier and a filter capacitor. Will look into that later. This brings up the point that many encoders may need signal conditioning, may want to make a board for that, not sure how to make it general on the H Bridge.
I am trying to hook up this motor and see what channels A and B are sending. I am confused about pins 3,4, and 5. Please help me out.
You said you hooked up a resistor (~500 Ohms) between the signal line and sensor ground. Will that be between pin 5 (red) and lets say arduino? I think pin 5 sends one pulse every time it makes a full rotation.
You also said the encoder power line seems to work if provided 10mA – 20mA, and quickly shorts. Does this mean that I need to put about 500 Ohms resistor on pin 3 (yellow) before I connect it to 5V?
Thanks,
Seon Han
To be clearer, motor channels A and B are the motor inputs, one should be motor ground and one should be motor power (reversing A and B reverses direction).
If my memory works, pin 5 should send a pulse every time the fingers on the disk go between the LED and the sensor, I was getting something like 40? pulses per revolution (not sure). I’m not sure if you need the resistor if you are connecting it to an arduino, I needed it because if it was just connected to the oscilloscope it couldn’t sink any current so the voltage did weird things, I just had the resistor going to ground, with the probe upstream of the resistor. I haven’t tried with an arduino or other mcu yet. I’d just connect pin 5 to an input interrupt pin on the arduino and see if it works first.
Using a 500 Ohm resistor will probably be fine, that would set the current to ~8mA. Definitely do not directly connect pin 3 to 5V directly. If it doesn’t work, maybe try setting the current to 15mA with a ~250 ohm resistor. I was just using a bench power supply in constant current mode, and am guessing about the upper end of the current range. 10-20mA is a pretty standard LED current though, I’m guessing that it is powering an IR led.
Hello, there is a detailed description and datasheet of this DC motor with encoder on this Chinese Website, you can still check the specs since the specs are partly in English in the pic. Check it out! Hope this could help. If you need any help in translating some part, just let me know.
http://detail.tmall.com/item.htm?spm=a230r.1.14.1.1bFo1Z&id=41623416570&ns=1&abbucket=4
I am getting a good 2.8v swing with 5 volt supply.
I don’t have colour wires but going from the two motor wires on the connect as 1 and 2- I’d say the Mitusmi M28N-1 Pinout is:
Blue (1): Motor A
Green (2): Motor B
Yellow (3): +5V – this is connected to the LED anode AND the Photo transistor collector.
Black (4): Led cathode through 220 ohm resistor to ground to light her up.
Red (5): photo-transistor emitter Encoder Signal though 10M resistor to ground gives a good signal.
Now she drops 2.8 volts which is reliable for reading and easy to process.